Looking on Amazon there are a number of head options.
013G5023 and 013G6040 appear to be for newer valves but this one which is described as being for old ra/vl 26mm bodies:
Danfoss - Thermostatic head for old Danfoss RA / VL 26mm bodies
I actually purchased the head recommended above but it didn't fit. I contacted that company and provided the naked valve photo and they advised me which head to purchase. Just gotta return the first one.
I updated this thread so anyone searching for a solution to the same problem would find the solution.